<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    城市:
    <select>
        <!-- select下拉菜单 -->
        <option>北京</option>
        <!-- 默认第一个option为默认选项 -->
        <option selected>南京</option>
        <!-- 加selected属性使其变成默认选项 -->
        <option>上海</option>
        <option>广州</option>
        <option>深圳</option>
        <option>武汉</option>
    </select>
</body>
</html>